A discarded soda bottle filled with an unidentified green liquid was found at the station during morning rush hour, Amtrak officials said. The substance did not pose a threat to passengers and was removed for testing.

A majority of the station was reopened by about 10:45 a.m., more than an hour after it was closed.

Officials in New York revealed the threat Thursday, saying an FBI source warned that terrorists had plotted to bomb the subway in coming days. But Homeland Security officials in Washington downplayed the threat, saying it's of "doubtful credibility."

A half mile away at the Port Authority Bus Terminal on Friday, more officers were visible on the streets, and one lane of traffic on Ninth Avenue was reserved for emergency vehicles